Such cycles, developed from a basic cycle described in U.S. Pat. No. 3,176,444 and comprising a fairly long elution step, are used in particular for the production of medium purity oxygen from air.
The present invention has for its object to provide a new process permitting, without any supplemental investment and by simple modification of the control regime of the cycle, obtaining substantially improved performances with a substantial reduction of specific energy consumption, particularly for the production of oxygen of a purity greater than 90%.
To do this, according to one characteristic of the invention, step b) of initial depressurization comprises a second phase b.sub.2, preceding the phase c) in which the depressurization is also effected countercurrent, elution step d) being followed by a countercurrent recompression phase f) with gas from another adsorber in phase b.sub.2.
According to other characteristics of the invention: